The present disclosure relates to a radiation image pickup device subjecting radiation represented by α-rays, β-rays, γ-rays, and X-rays to wavelength conversion, thereby reading information based on the radiation.
In a radiation image pickup device (radiation reader), electric charge based on input information after being subjected to photoelectric conversion in a photoelectric conversion section (photoelectric conversion element) is converted into a signal voltage, and thereby reading (imaging) of information based on radiation (for example, α-rays, β-rays, γ-ray, X-rays, or the like) is carried out.
When an image pickup section is configured by arranging a plurality of pixels, the interconnection length of a signal line to read a signal from the pixel increases according to a pixel number and thus, large parasitic capacitance may be formed. In that case, due to this large parasitic capacitance, an output voltage read from the signal line drops significantly.
Further, in such a situation, in order to perform moving-image reading, it is desirable to have sensitivity allowing image reading of, for example, about 30 sheets per second, and rapidity of movement. In particular, in a non-destructive inspection or the like including X-ray diagnosis in the medical care, there is a demand for reduction of an X-ray dose in irradiation and thus, higher sensitivity is desired.
Therefore, a typical radiation image pickup device has such a configuration that a source follower circuit that reads a signal voltage corresponding to signal charge into a signal line is provided for every pixel (for example, see Japanese Unexamined Patent Application Publication No. 11-307756). According to this source follower circuit, high-speed signal reading is possible even when capacitance formed in the signal line is large.